The sensors are equipped with GPS receivers and cellphone technology that provide data showing their exact movements in the waterway in real time. They can also deliver information on pollution, salinity and other variables.

"The goal here is to be able to show the currents on a scale that was previously unknown, so we can understand better how the Delta works," UC Berkeley electrical engineer Alex Bayen said.

Each of the 100 sensors contains a consumer cellphone or its components that transmit a live signal to a computer.

"It's a tracker of sorts; it knows where it is and how fast it's moving and because it's floating along with the water, what it's doing is what the water is doing," UC Berkeley graduate student Andrew Tinka said.

The green dots displayed in the tracking program show where each device is at the moment.

Some sensors, with red tops, are passive, meaning they just float. Those with a yellow cap are active, equipped with propellers that allow them to move in the water.

"The robotic sensors that we built have the capability which has been exploited before which is the ability of the sensor to keep itself safe, to move into the center of the channel to avoid obstacles," Tinka said.

With the real time data and the mobility of these sensors, researchers say there's a variety of real-world applications.

"We hope to provide authorities with a technology that can be deployed on-demand in real-time for something that happened that was unanticipated, like a levee break, oil spill or any other contamination in water," Bayen said.

In an emergency like a levee break, the sensors could be dropped from a helicopter and if a cell signal is unavailable, they can communicate via two-way radio.